Drafting instrument



Aug, 22, 1950 A. s. KNOBLOCH DRAF'TING INSTRUMENT Filed March 12, 1946 Patented Aug. 22, 1950 UNITED STATES PATENT OFFICE DRAF'HNG INSTRUMENT Arthur S. Knobloch, Pittsburgh, Pa.

Application March 12, 1946, Serial No. 653,838

5 claims. (c1. ss-ml 1 This invention relates to a drafting instrument, and important objects and advantages thereof are to provide a drafting instrument of the character described, which is specially designed and intended for use in drawing screw thread angle 5 lines in pencil, which will facilitate and expedite the drawing of such angle lines with exceptionalA accuracy and uniformity, which is adjustable to adapt same for use in drawing screw thread angle lines of any generally required size, which is siml0 ple in its construction and arrangement, durable and efficient in its use, compact, conveniently op' erable, attractive in appearance, and comparatively economical in its manufacture and use.

With the foregoing and other objects as may l hereinafter appear, the invention resides in the y novel construction, combination and arrange-l` ment of parts herein specifically described and illustrated in the accompanying drawing, but it is to be understood that changes in the form, proproportions and details of construction may be resorted to that come within the scope of the claims-"t hereunto appended.

In the drawing wherein like numerals of reference designate corresponding parts throughout 2 the several views:

Figure 1 is a top plan View of a drafting instru-T ment, constructed in accordance with the invention, with the embodied slide member adjusted to the maximum size position. 3

Figure 2 is a sectional view on line 2 2, Fig- Y ure l.

Figure 3 is a top plan View of a modiiied form of the drafting instrument embodying the invention.

Referring in detail to the drawing I denotes an elongated, iiat body structure including an upwardly disposed portion 2, which is reduced in thickness relatively to the general thickness of the body structure by recessing the top face of the latter.

The forward edge 3, of the reduced portion 2, inclines at an angle to the right approximately thirty degrees from the vertical, and has a beveled upper part 4. A pencil stop 5 is formed at the upper end of the beveled edge part @l and projects forwardly beyond the edge of the latter.

A flat slide member 6 is carried by the body structure I. The rearwardly disposed connecting 5 portion 1, ofthe slide member, is recessed on its inner or under face to reduce the thickness thereof, and is positioned against the reduced portion 2 of the body structure. The thickness reductions their bottom surfaces will be disposed on an even plane, and preferably also their top surfaces.`

The slide member is adjustably secured to the body structure I by means of a bolt S and nut 9. The bolt is engaged in the reduced portion'2 of the body structure and extends through anv elongated slot I0, which is rformed in the connecting portion 'I of the slide member. The slot i0 is disposed to the right at an angle of approximately thirty degrees from the vertical for the purpose to be described.

The slide member 6 has a substantially V- shaped cut-out II in the upper portion thereof, and thev respective edge walls I2 and i3, of said cut-out II are beveled. The beveled edge wall I2 inclines to the leftv at an angle of approximately thirty degrees, and is positioned forwardly of and in opposed relation to the beveled edge part 4 of the reduced portion 2 of the Ibody structure I. The edge wall I2in conjunction with the opposed edge part 4 forms a substantially V-shaped angle notch I4, along the walls of 'which latter the screw thread angles are drawn in drafting operations.`

The beveled edge wall I3, of the cut-out II, is positioned rearwardly ofthe beveled edge part .4, of the reduced portion 2 of the body structure I, and is constructed to merely provide clearance facilitating drawing operations.

The body structure I and the associated 'slide member 6, while preferably constructed of Celluloid or analogous material, may obviously be constructed of any other suitable material without departing from the spirit of the invention.

As has been stated, the pencil stop 4 extends 5 forwardly beyond the beveled edge part 4, and

consequently said pencil stop projects forwardly into the anglenotch lll at the upper end of said edge part 4.

'I'he lower edge I5, of the body structure I,

0 is perfectly straight; and, in the use of the inof the portions 2 and I are such that when the 55 body structure and slide member are assembled A strument, is positioned' against a T-square or like straight edge. The slide member 6 is adjusted on the body lstructure by shifting the former` upwardly or downwardly on the latter to provide the size of the screw thread angles to be drawn by the aid of the'improved instrument. Dueto the angular position of the slot lli in the slide member 6, the angular disposition of the notch walls directly beneath the pencil stop 5, and the lower line or dot exactly at the lower angle of the angle notch I4, and by securing such adjustment by means of the screw 8 and nut 9, the device is in the position for use.

In drawing the screw thread angles, the draftsman fixes the point of his pencil on the drawing directly beneath the pencil stop 5. The entire instrument is then shifted rearwardly, or to the right along the T-square, until the beveled edge wall I2 strikes the xed pencil point. The draftsman now proceeds to draw the angle lines by moving the pencil downwardly along the edge wall I2 to the bottom of the notch I l. and upwardly from the latter along the beveled edge part 4, until the pencil point strikes against the pencil stop 5. The pencil point is now at the fixed position for drawing the following angle lines. This operation is repeated until the required number of screw threads have been drawn.

The modification of the device, shown in Figure 3, differs from the preferred form thereof above described, in that the body structure I5 is considerably wider than the body structure I, and the lower portion I1 thereof, is recessed on its lower face to shiftably overlap an associated scale graduated measuring rule I8. The rule I8 is provided with laterally disposed end projections I9 to allow its engagement with a T-square Without interference by the overlapping body structure portion I1. The body structure IB is provided with an opening through which the rule scale may be read. The upper wall of the opening 20 is beveled and provided with an indicator mark ZI. The rule I8 may be conveniently used in connection with the device to indicate the total length of the screw thread angles drawn during drawing operations.

The present invention provides a most efficient device of its kind, which may be economically manufactured, and conveniently and successfully employed for the purposes and in the manner herein set forth.

What I claim is:

1. A drafting instrument of the class described, comprising a at elongated body structure having a lower straight edge, a slide member adjustably connected with said structure, portions of said structure and member being shaped and disposed to provide a pair of opposed walls combinedly forming a substantially V-shaped notch, and a pencil stop carried at the upper end of one of said pair of walls and extending horizontally into said notch.

2. A drafting instrument of the class stated, comprising a flat elongated body structure having a lower straight edge, a slide member adjustably connected with said structure, portions of said structure and member being shaped and disposed to provide a pair of opposed walls combinedly forming a substantially V-shaped notch, said pair of opposed walls being beveled, and a pencil stop carried at the upper end of one of said lpair of walls and extending horizontally into the said notch.

3. A drafting instrument of the class described, comprising a flat elongated body structure having a lower straight edge, a slide member adjustably connected with said structure, portions of said structure and member being shaped and disposed to provide a. pair of opposed walls combinedly forming a substantially V-shaped notch, said pair of opposed walls being beveled, a pencil stop carried at the upper end of one of said pair of walls and extending horizontally into the latter, and means engaging in said structure and extending through said member operable for securing the latter in the adjusted position.

4. A drafting instrument of the class described, comprising a fiat elongated body structure having a lower straight edge, a slide member provided with an elongated slot connected to said structure, a portion of said structure being shaped and disposed to form a beveled wall inclining to the right at an angle from the vertical, a portion of said member being shaped and disposed to form a beveled wall inclining to the left at an angle from the vertical, said walls being'. opposed to each other and combinedly providingiA a substantially V-shaped notch therebetween' said member being adjustable on said structure to vary the size of said notch, a pencil stop carried at the upper end of said structure wall and extending horizontally into said notch, and means engaged in said structure and extending through said slot in said member for securing the latter in the adjusted position.

5. A drafting instrument of the class described comprising an elongated fiat body structure having a lower straight edge and including a forwardly and upwardly disposed body portion, the outer face of said body portion being recessed to reduce by one-half the thickness of the forward portion of said body portion, said reduced forward portion being disposed to incline toward the right at an angle from the vertical, a flat slide member formed with a V-shaped cut-out in the upper portion thereof, the inner face of said member being recessed to reduce by one-half the thickness of the rearward portion of said member, said reduced rearward portion being disposed at an angle conforming to the angular disposition of said reduced forward portion and overlapping the latter in contacting engagement, the upper part of the forward edge of said reduced forward portion being bevelled, the walls of said V-shaped cut-out being bevelled, the rear wall of said cut-out being disposed rearwardly of said bevelled upper part, the bevelled forward wall of said cut-out and said bevelled upper part combinedly providing a V-shaped notch therebetween, a bolt engaged in said reduced forward portion and extending through an elongated diagonally disposed slot formed in said reduced rearward portion. a nut engaged on said bolt operable for allowing the adjustment of said member on said structure to vary the size of said notch and for securing said member in the adjusted position on said structure, and a horizontally disposed projection extending forwardly from the upper end of said bevelled part into said notch and forming a pencil stop. g

ARTHUR S. KNOBLOCH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 51,248 Wells Nov. 28, 1865 303,368 Goldwaite Aug. l2, 1884 386,589 Jones July 24, 1888 1,877,341 Kurtz Sept. 13, 1932 FOREIGN PATENTS Number Country Date 276,002 Germany Jan. 25, 1914 

